The present invention relates to an eyeglass lens processing apparatus having a processing apparatus body for processing a peripheral edge of an eyeglass lens by use of a grindstone and a centrifugal separator for separating processing refuse (waste) and grinding water from drainage discharged from the processing apparatus body.
Upon processing the eyeglass lens, cooling grinding water is supplied to a contact portion between the grindstone and the lens. Processing refuse produced during the processing of the lens is discharged from the processing apparatus body together with the grinding water. Since drainage discharged from a processing chamber contains the processing refuse, it is necessary to separate the processing refuse from the grinding water. For this reason, a centrifugal separator is known, which is used to discharge the grinding water to the outside of a dewatering bin in such a manner that the dewatering bin into which the grinding water is introduced is rotated to separate the processing refuse from the grinding water (JP-A-2004-243452 and JP-A-2005-153134).
Incidentally, in the eyeglass lens processing apparatus using the centrifugal separator, it is necessary to appropriately maintain or manage a filtering state of the grinding water and a dewatering state of the processing refuse without discharging the drainage containing the processing refuse from the dewatering bin as much as possible. For example, it is necessary to extract and collect the processing refuse from the dewatering bin before a large amount of the processing refuse are accumulated in the dewatering bin to thereby considerably deteriorate a filtering performance. However, when the extraction of the processing refuse is not carried out at an appropriate timing, the grinding water is not filtered, and hence the dirty drainage is directly introduced into a tank for storing the grinding water. When the dirty drainage is introduced into the tank, a problem arises in that bubbles overflow from the tank. Further, when the processing refuse are mixed with the grinding water supplied during the processing process, a problem arises in that a lens surface cannot be processed with high precision.
Additionally, in the centrifugal separator, the dewatering bin starts to rotate after the drainage is introduced from the processing apparatus body into the dewatering bin. At this time, since the dewatering bin cannot rotate at the maximum rotating speed at the beginning of the rotation, at the first stage, the filtering efficiency and the dewatering efficiency are low. For this reason, when a large amount of drainage is continuously introduced, the drainage may easily overflow in a state where the processing refuse are not sufficiently separated therefrom. Additionally, when the rotation of the dewatering bin stops at a stage when the processing of the lens ends, the dewatering bin is in a state where the water is filled therein. As a result, since the processing refuse attached to a wall surface of the dewatering bin are dissolved in the water, a problem arises in that the next rotation becomes unstable or the processing refuse cannot be easily extracted.